H H₂N Z 6=014 #2 N N R H ни HW H H H₂ N öfö-H HM #₂ N 8-0x0-G R HM A 3. A seminal paper on the reaction of singlet oxygen with the DNA base guanine was published by C.S. Foote et al. in 2004, less than two years before his untimely death (J. Am. Chem. Soc. 2004, 126, 16777-16782). Please read this paper and answer the following questions. As an aside, if you like a difficult NMR puzzle, you might enjoy this paper which is a masterpiece of structure determination by NMR. (a) Provide a mechanism for the formation of 8-oxo-G from guanine and singlet oxygen; your class notes may be helpful. (b) The authors found that the 8-oxo-G adduct from singlet oxygen and guanine reacts further to an unusual spiro compound.